This invention relates to a read head for reading a token or coin having a Wiegand wire therein, and is particularly directed to a read head for use in, for example, coin-operated machines, such as gambling machines, and which is capable of detecting the insertion of such coins/tokens by providing an electrical pulse in response to a switch in state of the Wiegand wire in the inserted token.
The Wiegand wire is a ferro magnetic wire having core and shell portions with divergent magnetic properties. The currently preferred type of Wiegand wire is disclosed in U.S. Pat. No. 4,247,601, issued on Jan. 27, 1981, and which is incorporated herein by reference. Read heads which are effective to provide an output pulse from a switch in state of the Wiegand wire are described in U.S. Pat. No. 4,263,523, issued Apr. 21, 1981, and U.S. Pat. 4,593,209, issued Jun. 3, 1986. A module employing the Wiegand wire that is effective to generate a pulse in response to a change in magnetic field is described in U.S. Pat. No. 4,484,090, issued Nov. 20, 1984.
Read heads for use with a Wiegand wire are currently employed in various access systems. Codes are incorporated in access cards and keys where the Wiegand wire is employed in the card or key to provide the encoding. One technique of positioning these wires in the access card and for reading the wires as the wires are passed over the face of a read head is described in said U.S. Pat. No. 4,593,209. The manner in which the Wiegand wires are encoded on a code strip carried in an access card is described in connection with the discussion of FIGS. 5 and 6 in said U.S. Pat. No. 4,593,209. As shown therein, the "zero" bit wires are all parallel to one another in a single column like the rungs of a ladder. The "one" bit wires are also parallel to one another in a single column. However, the center lines of the two columns are spaced from one another. Thus, the zero bits are read by one portion of the read head and the one bits are read by another portion of the read head. U.S. Pat. No. 4,736,122 discloses an improved read head of those devices discussed in the patents mentioned above. As shown in FIG. 1 of U.S. Pat. No. 4,736,122, the read head described therein is E-shaped with a polarized magnet at each of the three legs and the magnets are sandwiched between a thin yoke and a thick yoke. The thin and thick yokes forming set and reset fields, respectively.
The read head designs previously known have maximum air gap ranges that limit their usefulness to only select applications. For example, the above-mentioned access card having Wiegand wires therein can be read by previous read heads due to the relatively short distance between the Wiegand wires themselves and the face of the read head. Further, such read heads are inappropriate for reading Wiegand wires that do not by themselves represent either a zero bit or a one bit, such as Wiegand wires that are embedded within a novel coin or token.
It is therefore an object of this invention to provide a read head that has a greater air gap range than that of previous devices.
It is another object of this invention to provide a read head that is capable of reading a novel coin or token having one or more Wiegand wires therein.
Various other objects, advantages and features of the present invention will become readily apparent to those of ordinary skill in the art, and the novel features will be particularly pointed out in the appended claims.